Contemporary business has embraced two technologies that allow an individual employee to be more efficient and productive. The first of these technologies is voice messaging technology. In conventional voice messaging technology, a caller first calls an intended recipient by telephone. If the recipient of the call is absent, the caller is automatically connected to the recipient's voice messaging system. This system enables the caller to record a message for the recipient-subscriber in the caller's own voice, which message is then stored in an electronic format by the system. When subscriber calls into the system, he can play back the voice message on his telephone by issuing suitable commands.
The second technology effecting modern business practices is the facsimile machine or telecopier, which enables a sender to transmit a text or visual image (collectively "data") via electronic medium to a remote location, where the text or image may be printed out. Conventional facsimile technology requires telecopy equipment at both the sending and receiving stations, the first to encode the transmittal into electronic format and the latter to decode the transmittal back to a text or visual image suitable for printing.
Voice messaging and telecopy technologies have freed the employee from his office, and have enabled the businessman to conduct a large part of his work away from his home office. By calling in to his office from a remote location, the executive can listen to voice messages. Likewise, the facsimile machine has enabled the businessman to receive text or visual images virtually anywhere in the world accessible by public telephone lines.
An evolution of facsimile technology is the ongoing development of methods and apparatus for receiving and storing in electronic format the electronic representation of a facsimile transmittal. Such systems, known generically as "Fax Mail" systems, permit an incoming telecopy transmittal to be stored on a data storage system in electronic form, for later recall by the system subscriber. In this manner, the intended recipient may, for example, call into the office from a remote location, determine that a facsimile transmittal is available for him, and then direct that the text or image stored on the system be transmitted for printout to a facsimile machine at the remote location.
Previously known telephone answering systems have employed different integrated circuit components for receiving and transmitting voice information and text or image information. For example, in the Aspen(TM) telephone answering system sold by Octel Communications Corporation, Milpitas, Calif., voice signals received by the system are processed through an Analog Line Card ("ALC") which discretizes the signal into a digital electronic format using conventional voice processing techniques. Such analog processing circuitry is not suitable, however, for processing digital data, or for interpreting dual-tone modulated frequency (DTMF) signals (typically referred to as "Touchtones").
Voice system manufacturers have heretofore provided separate integrated circuit modules to enable their voice processing systems to receive or transmit text or image data. For example, Octel Communications Corporation provides the 500D Data Module, to enable their voice mail systems to receive and transmit facsimile messages. The 500D Data Module requires a dedicated communications port separate from those channels used for recording and transmitting voice messages, because a different protocol is used in processing data rather than voice signals.
A drawback common to previously known telephone answering systems with the ability to receive either voice signals or data was the inability to permit the caller, on a continuing basis, to vary the type of incoming signal. For example, in systems such as the 500D Data Module, once the incoming call was determined to be either voice or data, it was directed to the voice or data port of the telephone answering system for the duration of the transmittal. Thus, these systems had no ability to instantaneously monitor the incoming signal and to switch between voice and data processing as required for a particular incoming signal.
It would therefore be desirable to provide an integrated circuit board for receiving and transmitting voice signals and data over a single communications line, and which has the ability to discriminate and switch between voice and data processing modes as required to properly receive the incoming signal.
It would further be desirable to provide an integrated circuit board having single port voice and data capability in the form of a digital line card, so that the card could be readily interchanged to upgrade a conventional analog line card.